Centre Number
Candidate Number
Write your name here
Surname
Other names
Total Marks
Paper Reference
Edexcel GCE
Biology
Advanced Subsidiary
Unit 4: The Natural Environment and Species
Survival
Wednesday 16 June 2010 – Morning
Time: 1 hour 30 minutes
You do not need any other materials.
6BI04/01
Instructions
•
Use
black
ink or ball-point pen.
•
Fill in the boxes
at the top of this page with your name,
centre number and candidate number.
•
Answer
all
questions.
•
Answer the questions in the spaces provided
–
there may be more space than you need
.
Information
•
The total mark for this paper is 90.
•
The marks for
each
question are shown in brackets
– use this as a guide as to how much time to spend on each question.
•
Questions labelled with an
asterisk
(
*
) are ones where the quality of your
written communication will be assessed
– you should take particular care with your spelling, punctuation and grammar, as
well as the clarity of expression, on these questions.
•
Candidates may use a calculator.
Advice
•
Read each question carefully before you start to answer it.
•
Keep an eye on the time.
•
Try to answer every question.
2
*N37095A0224*
Answer ALL questions.
Some questions must be answered with a cross in a box . If you change your mind about an
answer, put a line through the box and then mark your new answer with a cross .
1
Forensic scientists use several different types of evidence to estimate the time of
death of a body.
(a) Place a cross in the boxes next to the
two
types of evidence that could be used
by a forensic scientist to estimate the time of death of a body.
(2)
Degree of muscle contraction
Length
of
fingernails
Signs
of
decomposition
Skin
pigmentation
(b) The core temperature of a body can also be used to estimate the time of death.
This can be recorded by measuring the temperature of the rectum.
The table below shows the mean core temperature, measured at 2-hour intervals
after death, using data from a large number of bodies. The standard deviation
from each of the means is also shown.
Time after death
/ hours
Mean core temperature
/ °C
Standard deviation from
the mean / °C
2
36.7 0.9
4
36.0 1.1
6
35.3 1.3
8
31.3 1.5
10
29.6 1.7
12
28.1 2.0
14
26.7 2.3
16
25.5 2.6
18
25.0 2.9
20
23.6 3.1
22
22.8 3.3
24
22.3 3.4
Explain what the data indicates about the reliability of using core temperature to
estimate the time of death.
(4)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(c)
Suggest
three
factors that could influence the rate at which a body cools after
death.
(3)
1
. . . .2
. . . .3
. . . .4
*N37095A0424*
2
It has been estimated that only 5% of the light energy hitting the surface of a leaf
reaches the chloroplasts to be used in the synthesis of organic material. The total
energy used in this synthesis is known as the gross primary productivity (GPP).
(a)
Suggest
two
reasons why 95% of the light hitting the surface of a leaf is not used
by the chloroplasts.
(2)
. . . . . . . . . . . . . . . . . . . . . . . .
(b) The mean GPP for plants on Earth is 24.4 × 10
6
J m
–2
year
–1
.
The plants use 3.7 × 10
6
J m
–2
year
–1
of this energy in metabolic processes. The
energy in the remaining organic material is known as net primary productivity
(NPP).
(i) Explain what is meant by the unit
J m
–2
year
–1
.
(1)
. . . . . . . .
(ii) Calculate the percentage of the mean GPP that remains as NPP within plants
on Earth.
Show
your
working.
(2)
(iii)
Place
a
cross in the box next to the metabolic process that best describes
the process that accounts for most of the difference between GPP and NPP in
plants.
(1)
A
Chemosynthesis
B
Respiration
C
Photosynthesis
D
Protein
synthesis
*(c) With reference to the structures in a chloroplast, explain how the energy from
light is made available in ATP molecules for the synthesis of organic materials.
(6)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6
*N37095A0624*
3
Filamentous algae are simple photosynthetic organisms that consist of long strands
of very similar eukaryotic cells. Each of the cells in the strand is enclosed within a
cellulose cell wall. The strand increases in length as the cells divide and elongate.
The photographs below show some cells in strands of a filamentous alga, as seen
using a light microscope.
(a) (i) Put a cross in the box next to the term that describes the process involved
in the cell divisions in a filamentous alga.
(1)
A
exocytosis
B
meiosis
C
mitosis
D
osmosis
(ii)
Put
a
cross in the box next to the structure that would
not
be found in a
cell from the strand of a filamentous alga.
(1)
A
lysosome
B
mitochondrion
C
plasmid
D
ribosome
(b) An investigation was carried out into the effect of temperature on the rate of
growth of a filamentous alga. Several short strands of the alga were placed into
culture solutions which were kept at five different temperatures and at a high light
intensity.
The number of cells in the strands, in each culture solution, was counted at the
beginning of the time period and again after 18 days.
The rate of growth was then calculated.
8
*N37095A0824*
The results of this investigation are shown in the graph below.
(i) Name
the
independent
variable in this investigation.
(1)
. . . .
(ii) Using the information in the graph, describe and suggest explanations for the
effect of temperature on the rate of growth of the filamentous alga.
(4)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .^
^
^
^
^
1.0 –
0.9 –
0.8 –
0.7 –
0.6 –
0.5 –
0.4 –
0.3 –
0.2 –
0.1 –
0 –
12
14
16
18
20
22
24
26
Temperature / °C
(iii) Suggest why it was important that this investigation was carried out at a high
light intensity.
(3)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(iv)
Suggest
two
abiotic factors, other than light intensity, that would need to be
controlled in this investigation.
(2)
1
. . . .2
. . . .10
*N37095A01024*
4
Various non-specific responses of the body are involved in resistance to bacterial
infections.
(a) Histamine, interferon and lysozyme are three substances involved in non-specific
responses to infection.
For each of the following statements, put a cross in the box next to the name of
the substance involved.
(i) Enzyme released in secretions that break down the cell walls of bacteria.
(1)
A
Histamine
B
Interferon
C
Lysozyme
(ii) Inflammation caused by a chemical released by white cells in connective tissue.
(1)
A
Histamine
B
Interferon
12
*N37095A01224*
(b) The flow diagram below summarises some of the stages of phagocytosis, a
non-specific response to a bacterial infection.
(i) Identify
D
,
E
,
F
,
G
and
H
by writing appropriate terms in the spaces below.
(5)
D
. . . .E
. . . .F
. . . .G
. . . .H
. . . .E
produce
F
which bind to
D
and label
bacteria
Labelled bacteria attach to
F
receptors
on
G
G
engulfs labelled bacteria by forming
vacuoles
Bacteria with
D
on surface enter blood
(ii) Explain why the processes shown in the flow diagram will only happen in
response to some types of bacteria.
(3)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
*N37095A01424*
5
Protein synthesis in cells involves molecules of DNA and RNA.
(a) The table below describes some features of the molecular structure of DNA and
RNA. Place a tick (
9
) in the box next to each statement to show whether it applies
to DNA only, RNA only or to both DNA and RNA.
(2)
Description
DNA only
RNA only
Both DNA
and RNA
Polymer formed from a single
strand of nucleotides
Pentose present in the
nucleotides
Adenine, cytosine, guanine
and thymine present
Nucleotides linked by
phosphodiester bonds
(b) The diagram below shows the sequence of the
last
six amino acids in a protein
molecule.
The tRNA anticodon that corresponds to each amino acid is also shown.
amino acids
tRNA anticodon
Alanine
CGA
Glutamine
GUU
Glycine
CCA
Asparagine
UUA
Proline
GGA
Valine
CAA
Using this information, explain how each of the following processes leads to the
synthesis of this sequence of amino acids.
(i) The formation of mRNA during transcription in the nucleus
(ii) The translation of mRNA into the sequence of amino acids in a ribosome
(3)
. . . . . . . . . . . . . . . . . . . . . . . .
(c) Suggest why the final triplet of nucleotides, on the strand of mRNA involved in the
synthesis of this sequence of amino acids, did not correspond with any anticodon
on tRNA.
(2)
. . . . . . . . . . . . . . . . . . . . . . . .
16
*N37095A01624*
6
Rhododendrons are shrubby plants that are widely distributed throughout the
northern hemisphere.
The flowering periods and habitats of two species of rhododendron, found on
Yakushima Island in Japan, are shown in the table below.
Species
Flowering period
Main flowering
period
Habitat
Rhododendron
eriocarpum
April to July
May
Rocky areas in
lowland regions
Rhododendron
indicum
May to July
June
High mountainous
regions
Where these populations overlap, hybrid plants are found that have arisen as a result
of cross-fertilisation between these two species. These hybrid plants are capable of
flowering and producing viable seeds.
(a) Suggest why some scientists might prefer to classify
Rhododendron eriocarpum
and
Rhododendron indicum
as varieties within the same species rather than as two
separate species.
(3)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .(b) (i) Explain what is meant by the term
genetic diversity
in a species.
(2)
(ii) Explain why there is likely to be a greater genetic diversity in the hybrid plants
than in either of the two separate species.
(2)
. . . . . . . . . . . . . . . . . . . . . . . .
*(c) Explain how the two different species of Rhododendron on Yakushima Island may
have evolved from a single population of an ancestral species.
(6)
18
*N37095A01824*
7
Several species of woodlice can be found in most gardens in Britain. Woodlice have
bacteria in their digestive system that secrete enzymes required for the digestion of
plant cell walls. Woodlice are decomposers of dead plants.
The photograph below shows one of the common species of woodlouse found in
gardens in Britain.
Magnification x10
Amateur Entomologists Society /
Kieren Pitts
(a) Suggest how woodlice are involved in the recycling of carbon.
(3)
(b) A student was watching woodlice in her garden. She noticed that woodlice on an
area of paving slabs were fairly active and running about. When she lifted some of
the stones near the slabs, the woodlice under these stones were relatively inactive
at first. However, within a very short time these woodlice started to run about.
After a few minutes, almost all of the woodlice that were under the stones had
disappeared from view.
(i) The student thought that the behaviour and distribution of the woodlice
were being influenced by an abiotic factor in her garden.
Place
a
cross in the box next to the term that describes this type of idea.
(1)
A
Hypothesis
B
Observation
C
Prediction
D
Theory
(ii)
Suggest
two
examples of abiotic factors that might influence the behaviour
and distribution of the woodlice in her garden.
(2)
1
. . . .20
*N37095A02024*
(c) She decided to investigate the behaviour of the woodlice. She collected ten
woodlice and released them into the centre of the area of paving slabs. She took
photographs immediately after the woodlice were released (time 0) and each
minute for ten minutes. This was repeated twice. Using the photographs, she
recorded the number of woodlice on the paving slabs at one-minute intervals.
Her results are shown in the table below.
Time after
release
/ minutes
Number of woodlice on paved area
1st release
2nd release
3rd release
Mean
0
10
10
10
10
1
10
9
9
9
2
9
8
9
9
3
7
7
7
7
4
7
6
5
6
5
6
6
6
6
6
4
5
4
4
7
4
3
4
4
8
3
3
2
9
0
2
1
10
1
1
0
(i) Complete the table by calculating the mean for each of the final three
minutes.
(ii) Suggest why taking photographs is a suitable method to count the woodlice.
(2)
. . . . . . . . . . . . . . . .
(iii) Explain why it would be difficult to determine which abiotic factor is
influencing the behaviour and distribution of the woodlice in a garden
environment.
(3)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
22
*N37095A02224*
8
Antibiotics are used to treat bacterial infections in eukaryotic organisms.
(a) The table below describes some of the structures that are found in cells. Complete
the table by writing the name of each of the structures described and stating
whether it is found in prokaryotic cells only
(P)
, eukaryotic cells only
(E)
or both
types of cell
(B)
.
(3)
Description
Name of structure
P, E or B
Enclosed by outer smooth
membrane;
inner membrane folded
forming cristae
Long strand-like structure
extending out from the cell;
used for locomotion
Small, circular loop of
double-stranded DNA
(b) Vancomycin is an antibiotic that kills bacterial cells by preventing the synthesis of
peptidoglycan, a component of bacterial cell walls.
(i) State the term used to describe antibiotics, such as vancomycin, that kill
bacterial cells.
(1)
. . . .
(ii) Suggest how bacterial cells are killed by vancomycin.
(2)
(iii) Explain why doctors have been advised to limit the prescription of antibiotics.
(2)
. . . . . . . . . . . . . . . . . . . .
(c) Describe how you could investigate the effect of different antibiotics on bacteria.
(4)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
